It is known to use carboxymethylated cellulosic materials in situations where a high degree of moisture absorbency is required. For example, WO93/12275 describes the production of various absorbent products such as disposable nappies (diapers), tampons, sanitary napkins, incontinence pads and the like. The advantage of carboxymethylated cellulosic materials, for example the carboxymethylated solvent-spun cellulose (lyocell) material to which WO93/12275 is particularly directed, is that they are capable of absorbing many times their own weight of water or aqueous fluid. This causes the carboxymethylated fibres to form a gel, which effectively serves to entrap the absorbed moisture.
One application in which absorption of moisture is of importance is the dressing of wounds, particularly exuding wounds. Carboxymethylated lyocell materials have been successfully utilised in wound dressing materials, and their use for this purpose is described, for example, in WO94/16746 and WO00/01425. The gel-forming characteristic of such materials is of particular advantage in the treatment of wounds, since the gel tends to prevent adherence and therefore minimises the wound damage and pain which can often occur when a wound dressing is removed. The attention of the reader is directed to the full disclosures of these documents for a fuller discussion of the preferred degree of carboxymethylation to achieve optimal results, and of the reaction conditions by means of which carboxymethylation may advantageously be achieved in practice.
The techniques described in these documents have resulted in commercially successful wound dressings, which are essentially flat but flexible, for example rectangular, circular or of some other planar shape and which comprise a wound-contacting portion composed of carboxymethylated lyocell fibre or fabric, often used in conjunction with an adhesive backing layer to provide adhesion to an area of skin adjacent to or surrounding the wound. Such dressings have proved to be very effective in the treatment of localised wounds and are particularly superior to conventional dressings composed of fibrous gauzes and waddings for use with moist or exuding wounds. However, their usefulness is limited in respect of large-scale wounds (such as extensive burns) and in fragile areas (such as may be associated with cancerous or fungating wounds), where the use of adhesive attachment means is difficult. Dressing retention can also be a problem in awkwardly shaped parts of the body such as armpits.
It is also known to provide wound dressings composed of certain materials in the form of a garment or an inflexible three-dimensional shape complementary to the shape of a body part. For example, GB 2,357,286 discloses a process for preparing a shaped polyurethane article for use as or in a wound dressing, for example a glove dressing for a whole hand, in which a last having the desired three-dimensional shape is provided, an aqueous layer is applied over the last, a layer of an isocyanate-capped prepolymer is applied over the last to react with the aqueous layer and form a polyurethane foam layer, which is then stripped from the last. Also, U.S. Pat. No. 5,437,621 discloses a medical dressing for covering a wound, for example in the shape of a glove, comprising material having at least three layers, namely an innermost layer comprising a porous polyethylene film which enables moisture to be wicked away from the injury, a middle layer comprising an absorbent material for absorbing the moisture from the innermost layer, and an outer layer comprising a flexible, waterproof and breathable material. Other body-shaped wound dressings are disclosed in EP 0,769,283 and WO86/04811.
To the best of our knowledge, however, it has not previously been suggested to provide body-shaped wound dressings incorporating a carboxymethylated cellulosic fabric. This may well be because it can be difficult to create a body-shaped wound dressing from carboxymethylated cellulosic fibre because of the inherent weakness of such fibre, which may preclude normal knitting into body-shaped format such as gloves, and because of the need to keep the fibre dry during processing to stop it absorbing moisture and becoming sticky.
The present invention therefore seeks to provide improved wound dressings in the form of body-shaped components having a wound-contacting surface and methods of manufacturing them.